Synthesis of 5-arylacetylenyl-1,2,4-oxadiazoles and their transformations under superelectrophilic activation conditions

• Andrey I. Puzanov,
• Dmitry S. Ryabukhin,
• Anna S. Zalivatskaya,
• Dmitriy N. Zakusilo,
• Darya S. Mikson,
• Irina A. Boyarskaya and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2021, 17, 2417–2424, doi:10.3762/bjoc.17.158

• vinyl triflates 4a–c with a predominant formation of Z-isomers as product of an anti-addition of TfOH to the acetylene bond (Scheme 3). E/Z-Stereochemistry of compounds 4a–c was determined by H,F-NOESY correlation between vinyl proton (>C=CH–) and the CF3 group from the TfO substituent (see Supporting

Strategies for the synthesis of brevipolides

• Yudhi D. Kurniawan and
• A'liyatur Rosyidah

Beilstein J. Org. Chem. 2021, 17, 2399–2416, doi:10.3762/bjoc.17.157

• . Analysis of data combination from ovicidal activity, mass spectrometry, and metabolomics using HPLC-diode array detector-MS (HPLC-DAD-MS), partial least squares regression analysis (PLS-DA), and a correlation map (univariate correlation analyses) enabled the prediction of compounds that have a positive

• correlation with biological activity. This analysis attributed two detected [M − H]− signals to dihydrobrevipolides C and F. Nevertheless, further structural identification was not performed. Conclusion The characteristic structural features of 5,6-dihydro-α-pyrone derivatives isolated from Hyptis brevipes

Isolation and characterization of new phenolic siderophores with antimicrobial properties from Pseudomonas sp. UIAU-6B

• Emmanuel T. Oluwabusola,
• Olusoji O. Adebisi,
• Fernando Reyes,
• Kojo S. Acquah,
• Mercedes De La Cruz,
• Larry L. Mweetwa,
• Joy E. Rajakulendran,
• Digby F. Warner,
• Deng Hai,
• Rainer Ebel and
• Marcel Jaspars

Beilstein J. Org. Chem. 2021, 17, 2390–2398, doi:10.3762/bjoc.17.156

• carboxamide C-10 (δC 172.9) and the quaternary carbon C-16 (δC 140.2), between H2-15 and H-18/20 to the quaternary carbon C-16, and a strong correlation from H-15 and H-19 to C-17/20 (δC 129.9). The new oxazoline derivative 5 was named pseudomonbactin B. The absolute configuration of the threonine residue in

Phenolic constituents from twigs of Aleurites fordii and their biological activities

• Kyoung Jin Park,
• Won Se Suh,
• Da Hye Yoon,
• Chung Sub Kim,
• Sun Yeou Kim and
• Kang Ro Lee

Beilstein J. Org. Chem. 2021, 17, 2329–2339, doi:10.3762/bjoc.17.151

• , and 118.0, respectively], indicating that compound 2 could be a stereoisomer of 5 at C-7 and C-8. The inspection of the COSY, HSQC, and HMBC spectra confirmed the planar structure of 2. The HMBC correlation of H-1′′ to C-4 indicated that the rhamnose unit was linked to the oxygen at C-4 and the

• methoxy groups [57.3 (×2)], and a glucose unit (δC 104.6, 78.6, 78.1, 75.8, 71.5, and 62.7). The location of the glucose unit was determined to be at C-4 by analysis of the HMBC data showing a correlation from H-1′ to C-4. The coupling constant (7.7 Hz) of the anomeric proton of glucose suggested that it

• location of the glucose unit was determined to be at C-4 based on the analysis of the HMBC data showing a correlation from H-1′ to C-4 (Figure 2). The HMBC cross-peaks of H-2′/C-7′′ and H-6′/C-7′′′ also indicated the presence of two galloyl groups at C-2′ and C-6′ of the glucose unit, respectively (Figure

Post-functionalization of drug-loaded nanoparticles prepared by polymerization-induced self-assembly (PISA) with mitochondria targeting ligands

• Janina-Miriam Noy,
• Fan Chen and
• Martina Stenzel

Beilstein J. Org. Chem. 2021, 17, 2302–2314, doi:10.3762/bjoc.17.148

• localization for the employed samples, despite carrying a mitochondria target on its surface according to the the Pearson correlation coefficient shown in Table 3. Moreover, PPM-NP4-TPP represents notable lower co-localization into the mitochondria than PPM-NP4 (Figure 6 and Supporting Information File 1

• , Figure S2), which is supported by the calculation of the Pearson’s correlation coefficient (Table 3). The Pearson’s correlation coefficient – which is a statistical formula that calculates the correlation between two variables – decreases in number for the PPM-NP4-TPP micelles, indicating that less

Nomimicins B–D, new tetronate-class polyketides from a marine-derived actinomycete of the genus Actinomadura

• Zhiwei Zhang,
• Tao Zhou,
• Taehui Yang,
• Keisuke Fukaya,
• Enjuro Harunari,
• Shun Saito,
• Katsuhisa Yamada,
• Chiaki Imada,
• Daisuke Urabe and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2021, 17, 2194–2202, doi:10.3762/bjoc.17.141

• -cis configuration of the diene moiety was indicated by a NOESY correlation between H21 and H27. The absolute configuration of the dehydrodecalin moiety of 3 was tentatively assigned to be identical with 4 because 3 was considered as a biosynthetic precursor of 4 [20]. Compounds 1‒3 showed

Constrained thermoresponsive polymers – new insights into fundamentals and applications

• Patricia Flemming,
• Alexander S. Münch,
• Andreas Fery and
• Petra Uhlmann

Beilstein J. Org. Chem. 2021, 17, 2123–2163, doi:10.3762/bjoc.17.138

Progress and challenges in the synthesis of sequence controlled polysaccharides

• Giulio Fittolani,
• Theodore Tyrikos-Ergas,
• Denisa Vargová,
• Manishkumar A. Chaube and
• Martina Delbianco

Beilstein J. Org. Chem. 2021, 17, 1981–2025, doi:10.3762/bjoc.17.129

• are ideal probes to study polysaccharides at the molecular level and identify structure–property correlations. Access to synthetic polysaccharides facilitated the correlation of chemical structure with molecular conformations [5][6], intermolecular interactions [7][8], and biological response [9

• correlation between chain length and biological activity, significant effort has been put to chemically synthesize β(1–3)-glucans with well-defined lengths. In contrast to β(1–4)-glucans (i.e., cellulose), β(1–3)-glucans with a DP up to 20 can be dissolved in water [112], simplifying the synthetic process

Regioselective N-alkylation of the 1H-indazole scaffold; ring substituent and N-alkylating reagent effects on regioisomeric distribution

• Ryan M. Alam and
• John J. Keating

Beilstein J. Org. Chem. 2021, 17, 1939–1951, doi:10.3762/bjoc.17.127

• multiple bond correlation (HMBC)) was employed [27]. For example, (1H–13C) HMBC analysis of N-1 regioisomer 10 shows a 1H–13C correlation between the C-7a carbon of the indazole ring and the n-pentyl CH2 proton pair proximal to the indazole N-1 atom (Figure 2). No evident 1H–13C correlation was observed

• between the n-alkyl CH2 proton pair proximal to the indazole N-1 atom and the indazole C-3 atom, for N-1 substituted indazole regioisomer 10. Conversely, (1H–13C) HMBC analysis of N-2 substituted regioisomer 11, revealed a 1H–13C correlation between the alkyl CH2 proton pair (proximal to the indazole N-2

• atom) and the C-3 carbon of the indazole heterocycle, while no 1H–13C correlation was observed between the alkyl CH2 proton pair and the C-7a carbon atom of the indazole ring. With a set of optimal conditions for the regioselective N-1 alkylation of methyl ester 9 in hand (Table 1, entry 22), our

Development of N-F fluorinating agents and their fluorinations: Historical perspective

• Teruo Umemoto,
• Yuhao Yang and
• Gerald B. Hammond

Beilstein J. Org. Chem. 2021, 17, 1752–1813, doi:10.3762/bjoc.17.123

A systems-based framework to computationally describe putative transcription factors and signaling pathways regulating glycan biosynthesis

• Theodore Groth,
• Rudiyanto Gunawan and
• Sriram Neelamegham

Beilstein J. Org. Chem. 2021, 17, 1712–1724, doi:10.3762/bjoc.17.119

• cancer type must be greater than the median RPKM expression of the TF across all 29 different cancer types; ii) the RNA expression of the TF and target gene should be correlated. To determine this, Cistrome first compares the selected TF–gene correlation with a null distribution computed by randomly

• peaks [15][16]. In the current article, we passed the TF–gene relationships established in Cistrome Cancer DB to identify TFs potentially interacting with 341 glycogenes (Supporting Information File 3, Table S1). The two metrics for this selection were RP ≥ 0.5 and TF–glycogene expression correlation

• carbohydrates. Mining TF–glycogene relationships in Cistrome Cancer DB Regulatory potential and gene correlation data were downloaded from the Cistrome Cancer DB in tab-delimited form (http://cistrome.org/CistromeCancer/CancerTarget/) [14]. TF–gene relationships were filtered for the 341 glycogenes in this

Chemical approaches to discover the full potential of peptide nucleic acids in biomedical applications

• Nikita Brodyagin,
• Martins Katkevics,
• Venubabu Kotikam,
• Christopher A. Ryan and
• Eriks Rozners

Beilstein J. Org. Chem. 2021, 17, 1641–1688, doi:10.3762/bjoc.17.116

Methodologies for the synthesis of quaternary carbon centers via hydroalkylation of unactivated olefins: twenty years of advances

• Thiago S. Silva and
• Fernando Coelho

Beilstein J. Org. Chem. 2021, 17, 1565–1590, doi:10.3762/bjoc.17.112

• suggested that iridium serves as a π-Lewis acid (although one could propose a C–H activation pathway) that activates the olefin by coordination due to the correlation observed between the nature of the Ir counterion and the reaction yields. Radical-based approaches Olefin hydroalkylation via metal hydride

Chemical synthesis of C6-tetrazole ᴅ-mannose building blocks and access to a bioisostere of mannuronic acid 1-phosphate

• Eleni Dimitriou and
• Gavin J. Miller

Beilstein J. Org. Chem. 2021, 17, 1527–1532, doi:10.3762/bjoc.17.110

• of the PMB group on the tetrazole ring for each compound. For 11, a correlation of tetrazole Cq (δC = 150.4 ppm) with the benzylic protons of the PMB group (δH = 5.66 ppm, see Supporting Information File 1, Figure S3), was observable. Similar analysis for 12 indicated no such correlation. In order to

Cascade intramolecular Prins/Friedel–Crafts cyclization for the synthesis of 4-aryltetralin-2-ols and 5-aryltetrahydro-5H-benzo[7]annulen-7-ols

• Jie Zheng,
• Shuyu Meng and
• Quanrui Wang

Beilstein J. Org. Chem. 2021, 17, 1481–1489, doi:10.3762/bjoc.17.104

• 13C NMR chemical shift for C2 is expected to be in the range of 60 to 70 ppm and the assignment of H3 was based on the HSQC correlation between H3 and C2. Then, H1 and H2 could be assigned by COSY and HSQC experiments. Following that, NOE analysis was applied to analyze the relative cis- and trans

• -configuration. If there is an NOE correlation between H1 and H3, and meanwhile H1 and H3 also have a strong NOE correlation with H2a, the compound is assigned to be cis-configured. Otherwise, it was assigned to be the trans-isomer (see Supporting Information File 1 for details). Having determined the suitable

Analogs of the carotane antibiotic fulvoferruginin from submerged cultures of a Thai Marasmius sp.

• Birthe Sandargo,
• Leon Kaysan,
• Rémy B. Teponno,
• Christian Richter,
• Benjarong Thongbai,
• Frank Surup and
• Marc Stadler

Beilstein J. Org. Chem. 2021, 17, 1385–1391, doi:10.3762/bjoc.17.97

• (δH 4.89) and H-13 (δH 1.01) in the COSY spectrum (Figure 2). Furthermore, the relative configurations of C-6 and C-10 were elucidated by the ROESY correlation (Figure 3) depicted between H-6 (δH 2.57) and H-10 (δH 2.75). All these correlations also support the structure of compound 2. Metabolite 4

Antiviral therapy in shrimp through plant virus VLP containing VP28 dsRNA against WSSV

• Santiago Ramos-Carreño,
• Ivone Giffard-Mena,
• Jose N. Zamudio-Ocadiz,
• Alfredo Nuñez-Rivera,
• Ricardo Valencia-Yañez,
• Jaime Ruiz-Garcia,
• Maria Teresa Viana and
• Ruben D. Cadena-Nava

Beilstein J. Org. Chem. 2021, 17, 1360–1373, doi:10.3762/bjoc.17.95

• difficult. The correlation of the TEM and EMSA results suggests that the band in the agarose gel migrated slightly less than the wild type CCMV corresponds to, in multiple icosahedral capsids and short tubes with dsRNA. Similar results have been obtained with long ssRNA [42]. In contrast, the band that is

A new glance at the chemosphere of macroalgal–bacterial interactions: In situ profiling of metabolites in symbiosis by mass spectrometry

• Marine Vallet,
• Filip Kaftan,
• Veit Grabe,
• Fatemeh Ghaderiardakani,
• Simona Fenizia,
• Aleš Svatoš,
• Georg Pohnert and
• Thomas Wichard

Beilstein J. Org. Chem. 2021, 17, 1313–1322, doi:10.3762/bjoc.17.91

• and between thallus and rhizoid tissues. Significant features were searched in the PCA loading plots and also in the pattern hunter plots obtained from a correlation analysis based on the Pearson correlation coefficient R. A one-way ANOVA with Fisher's LSD post hoc test (P-value < 0.05) was performed

Stereoselective syntheses of 3-aminocyclooctanetriols and halocyclooctanetriols

• Emine Salamci and
• Yunus Zozik

Beilstein J. Org. Chem. 2021, 17, 705–710, doi:10.3762/bjoc.17.59

• correlation is due to the small coupling constant (J = 2.2 Hz). On the other hand, the resonance signal of H-3 appears as a doublet of doublets at 3.95 ppm with coupling constants of J = 8.6 and 2.2 Hz. The large coupling constant (J = 8.6 Hz) clearly supports the trans relation of the protons H-3 and H-4 and

• at 5.62 ppm is strong. This strong correlation is due to the large coupling constant (J = 8.7 Hz). The fact that the proton H-4 appears as a doublet of doublet of doublets with coupling constants of J = 13.1, J = 8.7, and 3.3 Hz also supports the trans relation (J = 8.7 Hz) of the protons H-4 and H-3

Menthyl esterification allows chiral resolution for the synthesis of artificial glutamate analogs

• Kenji Morokuma,
• Shuntaro Tsukamoto,
• Kyosuke Mori,
• Kei Miyako,
• Ryuichi Sakai,
• Raku Irie and
• Masato Oikawa

Beilstein J. Org. Chem. 2021, 17, 540–550, doi:10.3762/bjoc.17.48

• important NOESY correlation observed for 10* is also shown in Scheme 4. The conformational analysis of the (2S)-isomer carried out by CONFLEX (MMFF94S), however, was not very encouraging since the four contiguous single bonds between the heterotricycle and the menthyl group were found to be freely rotating

CF₃-substituted carbocations: underexploited intermediates with great potential in modern synthetic chemistry

• Anthony J. Fernandes,
• Armen Panossian,
• Bastien Michelet,
• Agnès Martin-Mingot,
• Frédéric R. Leroux and
• Sébastien Thibaudeau

Beilstein J. Org. Chem. 2021, 17, 343–378, doi:10.3762/bjoc.17.32

• correlation, established as log(k) = f(σ+), gave a linear dependence of the rate with the σ+ parameters of the aryl substituents, with a behavior in agreement with the transient formation of a carbenium ion. The slope of the straight line, ρ+ = −7.46, reflects the very high electron demand induced by the CF3

• obtained. Similarly, the nature of the aromatic substituent influenced the solvolysis rate, with an observed acceleration for substrates adorned with electron donor substituents and a deceleration for those carrying electron-withdrawing substituents. The Hammett–Brown correlation gave a straight line, with

• ]. The Hammett–Brown correlation considering derivatives 34 (Figure 6) gave a linear free-energy correlation with ρ+ = −3.98, which is approximately half the value of those previously reported for the benzylic α-CF3-substituted tosylate derivatives 13 substituted by a methyl group (Figure 2) [43][48

Exploring the possibility of using fluorine-involved non-conjugated electron-withdrawing groups for thermally activated delayed fluorescence emitters by TD-DFT calculation

• Dongyang Chen and
• Eli Zysman-Colman

Beilstein J. Org. Chem. 2021, 17, 210–223, doi:10.3762/bjoc.17.21

• lack of correlation between the computed |VSOC|2 × exp[−(ΔEST2)] and the experimentally determined krISC values. The significantly higher experimental krISC can be explained by the presence of intermediate triplet states leading to second order spin-vibronic coupling to mediate rISC in 5CzTRZ [24

Control over size, shape, and photonics of self-assembled organic nanocrystals

• Chen Shahar,
• Yaron Tidhar,
• Yunmin Jung,
• Haim Weissman,
• Sidney R. Cohen,
• Ronit Bitton,
• Iddo Pinkas,
• Gilad Haran and
• Boris Rybtchinski

Beilstein J. Org. Chem. 2021, 17, 42–51, doi:10.3762/bjoc.17.5

• - and morphology-dependent properties arising from confinement effects and strong interactions between neighboring atoms [1][2][3]. The correlation between nanoparticle size and the related electronic and optical properties has extensively been studied, leading to applications in novel technologies and

The fluorescence of a mercury probe based on osthol

• Guangyan Luo,
• Zhishu Zeng,
• Lin Zhang,
• Zhu Tao and
• Qianjun Zhang

Beilstein J. Org. Chem. 2021, 17, 22–27, doi:10.3762/bjoc.17.3

• selectivity for Hg2+. The fluorescence intensity of OST showed a good linear correlation with the Hg2+ concentration (6.0 × 10−5 to 24.0 × 10−5 mol∙L−1, R2 = 0.9954), and the detection limit of the probe was 5.04 × 10−8 mol∙L−1, which can be used for the determination of Hg2+ traces. Keywords: fluorescence

Molecular basis for protein–protein interactions

• Brandon Charles Seychell and
• Tobias Beck

Beilstein J. Org. Chem. 2021, 17, 1–10, doi:10.3762/bjoc.17.1

• strength dependence is β-lactamase and its protein inhibitor BLIP, where binding decreases significantly as the salt concentration increases [53]. Chen et al. analysed the structural and thermodynamic data of 113 heterodimeric complexes and discussed the correlation between binding affinity and amount of